If you've already got a Mag-Lite, you might want to replace the bulb with an Ever-LED
http://www.leddynamics.com/EverLED/
I've got a couple of them, and they'll outlive me. The Surefire tactical light was driving me broke. CR123 batteries aren't cheap, only lasted about an hour, and the bulbs were outrageously expensive, and only good for 20 hours. I junked the Surefire.